A Review on Adhesively Bonded Aluminium Joints in the Automotive Industry

Abstract

The introduction of adhesive bonding in the automotive industry is one of the key enabling technologies for the production of aluminium closures and all-aluminium car body structures. One of the main concerns limiting the use of adhesive joints is the durability of these system when exposed to service conditions. The present article primarily focuses on the different research works carried out for studying the effect of water, corrosive ions and external stresses on the performances of adhesively bonded joint structures. Water or moisture can affect the system by both modifying the adhesive properties or, more importantly, by causing failure at the substrate/adhesive interface. Ionic species can lead to the initiation and propagation of filiform corrosion and applied stresses can accelerate the detrimental effect of water or corrosion. Moreover, in this review the steps which the metal undergoes before being joined are described. It is shown how the metal preparation has an important role in the durability of the system, as it modifies the chemistry of the substrate’s top layer. In fact, from the adhesion theories discussed, it is seen how physical and chemical bonding, and in particular acid-base interactions, are fundamental in assuring a good substrate/adhesive adhesion.

A Model of Damage for Brittle and Ductile Adhesives in Glued Butt Joints

“…Within the last decades, adhesive bonding became a very common assembly technique in many industrial sectors, such as aeronautical (e.g., in composite aircraft to bond the stringers to fuselage and wing skins to stiffen the structures against buckling [1]), civil (e.g., in glass-fiber-reinforced polymer pultruded beams [2] or in carbon-fiber-reinforced polymer beams [3]), automotive (e.g., in both closures and structural modules [4]), and biomedical engineering (to fix implants in bone tissue in orthopedic or dentistry surgery [5]), as an alternative to conventional joining techniques, such as welding and riveting [6]. Adhesive bonding provides several advantages, including reduced stress concentrations, higher corrosion resistance, water tightness, and the ability to join materials with dissimilar properties.…”

“…Nevertheless, adhesive bonding still presents some disadvantages. One of the main concerns limiting the use of adhesive joints is their long-life durability when exposed to service conditions [4]. Corrosion and aging may cause micro-cracking phenomena that can be measured via non-destructive techniques [7].…”

A Review on Anodizing of Aerospace Aluminum Alloys for Corrosion Protection

“…However, no single theory can fully explain adhesion. Each of them seems to be more suitable for some specific applications and substrates than for others [88]. Among them, the adsorption and the mechanical theories are generally recognized to be the most suitable theories to explain adhesion between metal oxides and polymers [16,88].…”

“…These interactions account for the forces between permanent and induced dipoles. Even though these bonds are weak in comparison to chemical bonding, they take place between any two molecules in contact and consequently contribute to all adhesive bonds [88]. Conversely, the formation of a chemical bond depends on the ability to form a covalent or ionic bond between the oxide and the polymer.…”

Synthesis and Experimental Characterization of a MWCNT-Filled Bio-Based Adhesive

“…In the last decades, the epoxy-adhesive applications are expanding very fast to interior (cosmetic) and secondary structural applications in the aerospace [1,2], the automotive industries [3] and used in the construction industry in a semi-cured state [4]. At the same time, the new environmental restrictions are asking for polymers of lower environmental footprint, decreased production cost and increased recyclability [4,5].…”